The invention relates to improvements in apparatus for temporary storage of cigarettes of other rod-shaped articles of the tobacco processing industry. More particularly, the invention relates to improvements in apparatus for temporary storage of articles which are supplied by one or more article feeding conveyors are are evacuated by one or more article withdrawing conveyors. Still more particularly, the invention relates to improvements in apparatus wherein a collecting vessel can temporarily store articles when the rate of admission of articles exceeds the rate of withdrawal or evacuation, and which can satisfy the requirements of the evacuating means for a certain interval of time when the rate of evacuation exceeds the rate of admission.
Apparatus of the above outlined character are often used for temporary storage of filter rod sections or plain or filter cigarettes, cigarillos or cigars. Alternatively, such apparatus can be utilized to gather the output of two or more article feeding conveyors preparatory to evacuation of the accumulated articles from the collecting vessel for admission into a packing machine, into a filter tipping machine or into a magazine for longer-lasting storage.
If the collecting vessel is used for accumulation of rod-shaped articles which are about to be delivered to a tray filling apparatus, the conveyor or conveyors which admit the articles are normally designed to deliver articles along one or more horizontal paths. The tray filling apparatus can be disposed at a level below the collecting vessel so that the evacuating unit is designed to advance a mass flow of articles along a substantially vertical path. Alternatively, or in addition to the just described positioning of the evacuating means, the collecting vessel can be provided with a second outlet for evacuation of one or more layers of rod-shaped articles to a different destination, for example, to a packing machine.
It is further known to provide the collecting vessel with a so-called breathing cover which performs several functions. Thus, the cover can constitute a component of or it can carry an element of a level detector which monitors the accumulation of rod-shaped articles in the collecting vessel and serves to regulate the rate of admission of articles into and/or the rate of evacuation of articles from the collecting vessel. Furthermore, such level detector can be used to stop the article making machine when the collecting vessel is filled to capacity or when the article processing machine (such as the aforementioned tray filling apparatus or the aforementioned packing machine) is out of commission. In addition, the cover can serve as a means for preventing undesirable changes in the orientation of articles which are confined in the collecting vessel. As a rule, the articles are to be stored in the form of a stack of parallel articles.
U.S. Pat. No. 3,995,732 discloses an apparatus wherein the cover for the supply of rod-shaped articles in the collecting vessel comprises a membrane the ends of which are fixedly secured to the vessel. The apparatus further comprises a sensor in the form of a lever which rests on top of the membrane. It has been found that, when such apparatus receive rod-shaped articles at a high rate, the articles which enter the collecting space below the membrane accumulate into a pyramid and tension the central portion of the membrane so as to cause the lever to indicate that the vessel is filled at a time when the internal space of the vessel is capable of receiving a substantial quantity of additional articles. Thus, the nominal capacity of the vessel greatly exceeds the actual capacity.
U.S. Pat. Nos. 3,921,790 and 3,759,408 disclose modified apparatus wherein the cover comprises two pivotable levers one of which is mounted for pivotal movement in the upper region and the other of which is mounted for pivotal movement in the lower region of the space in the collecting vessel. The levers are sufficiently long to cross or overlap each other in the interior of the collecting vessel. A drawback of such apparatus is that the levers are likely to cause a misalignment of the admitted articles. Moreover, the levers are likely to cause the adjacent articles to jam so that the jammed and/or misaligned articles interfere with the mass flow of articles through the collecting vessel.